Nanoscopic Insights of Amphiphilic Peptide against the Oligomer Assembly Process to Treat Huntington's Disease.

Finding an effective therapeutic regimen is an urgent demand for various neurodegenerative disorders including Huntington's disease (HD). For the difficulties in observing the dynamic aggregation and oligomerization process of mutant Huntingtin (mHtt) in vivo, the evaluation of potential drugs at the molecular protein level is usually restricted. By combing lifetime-based fluorescence microscopies and biophysical tools, it is showcased that a designed amphiphilic peptide, which targets the mHtt at an early stage, can perturb the oligomer assembly process nanoscopically, suppress the amyloid property of mHtt, conformationally transform the oligomers and/or aggregates of mHtt, and ameliorate mHtt-induced neurological damage and aggregation in cell and HD mouse models. It is also found that this amphiphilic peptide is able to transport to the brain and rescue the memory deficit through intranasal administration, indicating its targeting specificity in vivo. In summary, a biophotonic platform is provided to investigate the oligomerization/aggregation process in detail that offers insight into the design and effect of a targeted therapeutic agent for Huntington's disease.

HAF mediates the evasive resistance of anti-angiogenesis TKI through disrupting HIF-1α and HIF-2α balance in renal cell carcinoma.

Anti-angiogenesis has emerged as a standard of care for metastatic renal cell carcinoma. However, long-lasting efficacy is seldom reached, and evasive resistance eventually occurs under anti-angiogenic tyrosine kinase inhibitor (TKI) therapy. To establish new therapeutic strategies, investigating the molecular mechanism of resistance is critically important. In our study, human umbilical vascular endothelial cells (HUVECs) were incubated with TKI treatment in conditioned medium derived from renal cancer cells (RCCs) to demonstrate cell viability. Quantitative real time PCR or Western blotting analysis detected the fluctuation of transcriptional factors HIF-1α and HIF-2α in RCCs under TKI treatment. We demonstrated the alteration of a specific cytokine produced from RCCs under normoxia or hypoxia incubation by utilizing a cytokine RT-PCR primer array. We found that the anti-angiogenic TKI sunitinib disrupted the balance between HIF-1α and HIF-2α in RCCs and led to a protective effect on HUVECs against sunitinib treatment when cultured with conditioned medium. Mechanistically, RCCs treated with sunitinib resulted in down-regulation of HIF-1α, but not HIF-2α, through reduction of both mRNA and protein levels. The down-regulation of HIF-1α by sunitinib occurred via hypoxia associated factor (HAF), which also enhanced HIF-2α transactivation activity to increase the production of pro-angiogenic factors and cytokines and promote HUVEC proliferation. This phenomenon was observed in ACHN and A498 cells, which express both HIF-1α and HIF-2α, but was not observed in 786-O cells, which express only HIF-2α. Our results illustrated that targeting both angiogenesis and hypoxia pathways might provide a resolution to dealing with the devastating effects of anti-angiogenesis resistance.

The HDAC inhibitor LBH589 induces ERK-dependent prometaphase arrest in prostate cancer via HDAC6 inactivation and down-regulation.

Histone deacetylase inhibitors (HDACIs) have potent anti-cancer activity in a variety of cancer models. Understanding the molecular mechanisms involved in the therapeutic responsiveness of HDACI is needed before its clinical application. This study aimed to determine if a potent HDACI, LBH589 (Panobinostat), had differential therapeutic responsiveness towards LNCaP and PC-3 prostate cancer (PCa) cells. The former showed prometaphase arrest with subsequent apoptosis upon LBH589 treatment, while the latter was less sensitive and had late G2 arrest. The LBH589 treatment down-regulated HDAC6 and sustained ERK activation, and contributed to prometaphase arrest. Mechanistically, LBH589 inhibited HDAC6 activity, caused its dissociation from protein phosphatase PP1α, and increased 14-3-3ζ acetylation. Acetylated 14-3-3ζ released its mask effect on serine 259 of c-Raf and serine 216 of Cdc25C subsequent to de-phosphorylation by PP1α, which contributed to ERK activation. Enhanced ERK activity by LBH589 further down-regulated HDAC6 protein levels and sustained ERK activation by free-forward regulation. The sustained Cdc25C and ERK activation resulted in early M-phase (prometaphase) arrest and subsequent apoptosis in the most sensitive LNCaP cells but not in PC-3 cells. This study provides pre-clinical evidence that HDAC6 may serve as a sensitive therapeutic target in the treatment of prostate cancer with HDACI LBH589 for clinical translation. This study also posits a novel mechanism of HDAC6 participation in regulating the c-Raf-PP1-ERK signaling pathway and contributing to M phase cell-cycle transition.

X protein of hepatitis B virus functions as a transcriptional corepressor on the human telomerase promoter.

UNLABELLED: The X protein of hepatitis B virus (HBx) is essential for transactivation of hepatitis B viral and host cellular genes. It has been specifically implicated in the development of hepatocellular carcinoma; however, the molecular mechanism remains unknown. Telomeres, the DNA-protein complexes at the ends of eukaryotic chromosomes, protect chromosomes from degradation at the terminal regions, fusion with a broken DNA end, and inappropriate recombination. The shortening of telomeres that occurs during hepatocellular carcinogenesis has been well studied. In the present study, we isolated an HBx isoform that resulted in telomere shortening in hepatoma cell lines. We found that this HBx isoform down-regulated the expression of human telomerase by transcriptionally repressing its promoter. To further determine the molecular mechanism, we examined human telomerase promoter and identified myc-associated zinc finger protein (MAZ) as a transcriptional repressor of the promoter. We found that the HBx isoform achieved transcriptional suppression of human telomerase by enhancing MAZ binding to its consensus sequence in the promoter through physical association with MAZ. CONCLUSION: The data suggest that HBx can induce telomere shortening by acting as a transcriptional corepressor of MAZ on the human telomerase promoter.